The present invention relates to a valve element as defined in the pre-amble of claim 1, which comprises a frame, at least one first inlet, at least one second inlet and at least one outlet.
The invention relates to so-called delay valves used in pressure medium systems to open a passage upon being triggered after a pressure difference has reached a pre-set value. As is known, such valves are rather complicated and, especially in the case of gaseous pressure mediums, problems have been encountered in respect of tightness. On the other hand, in applications where the valve elements may remain unused for very long times, e.g. in connection with fire extinguishing systems, reliable operation of the valve elements is also an important design factor.
The object of the present invention is to achieve a completely new type of solution that makes it possible to avoid the drawbacks of prior art. The object of the invention is to create a reliable apparatus that can be utilized especially in fire extinguishing applications.
The valve element of the invention is characterized by a combination comprising at least one burst disk (rupture disk) or equivalent, which, when unbroken, closes a passage from the second inlet at least to the outlet, and a piston element comprising a piercing element or the like for piercing the burst disk, said piston element being arranged to be movable between at least two positions when the burst disk has been pierced, in which first position the passage from the second inlet to the outlet is closed while in the second position the passage from the second inlet to the outlet is open, to which second position the piston element is moved after the pressure difference between the second inlet and the first inlet has reached a predetermined value.
The apparatus of the invention is additionally characterized by what is stated in claims 2–6.
The solution of the invention has numerous significant advantages. By using in the valve element a combination comprising a burst disk and a movable piston element that simultaneously acts as a valve stem, a tight delay valve solution that is reliable when triggered is achieved. The solution is very well applicable for use in high-pressure systems, e.g. in high-pressure extinguishing systems using water mist.